Composite articles, wear plates and methods

ABSTRACT

A metal matrix composite article is described that includes a metal component, a ceramic component, and a lubricious component. The metal matrix composite article has a first surface and a second surface. The lubricious component is present in an amount that is highest at the first surface and is lowest at the second surface. The ceramic component is present in an amount that is highest at the first surface and is lowest at the second surface. The metal component is present in an amount that is highest at the second surface and is lowest at the first surface. In some cases, the metal matrix composite article is a wear plate for a fifth wheel hitch.

CROSS-REFERENCES

This application claims the benefit of U.S. Provisional Application No.61/690,728, filed Jul. 3, 2012, and U.S. Provisional Application No.61/744,557, filed Sep. 28, 2012, the content each of which is herebyincorporated by reference in its entirety.

BACKGROUND

A fifth wheel hitch is commonly found on a truck tractor (e.g.,tractor-trailer cab) and is typically used for hauling largesemi-trailers. The fifth wheel hitch includes a hitch bearing plate thatis positioned in a substantially horizontal plane. A kingpin is coupledto a bearing plate located on a semi-trailer. The semi-trailer bearingplate is also positioned in a substantially horizontal plane. The hitchbearing plate receives the kingpin and locks it in place with a lockingmechanism. During use, the semi-trailer bearing plate rests upon andpivots on the upper surface of the hitch bearing plate to permit thetruck tractor and semi-trailer to articulate when turning whileremaining engaged together. The hitch bearing plate bears a largeportion of the semi-trailer weight and much friction occurs between thehitch bearing plate and the semi-trailer bearing plate during pivoting.

To reduce this friction, operators deposit a layer of grease between thehitch bearing plate and semi-trailer bearing plate. However, operatorsmust continually replace this grease layer in order to prevent wear anddamage to the respective bearing plates. In addition, grease isundesirable because it is environmentally unfriendly and very messy.Grease also attracts dirt and other debris, which in turn creates morefriction between the respective bearing plates plus excessive wear tothe same.

Others have replaced the layer of grease with a cover to the hitchbearing plate. The cover consists of a low-friction material such as apolymeric material. However, such a cover is made entirely of a singlelow-friction material that is not mechanically durable to withstanddirect engagement of the kingpin during coupling of the tractor to thetrailer or wear over a lifetime of the hitch bearing plate. As such, thecover often breaks or degrades such that it itself must often bereplaced. Replacing a cover is a costly, time consuming procedure and isnot desirable. Replacement of the cover is a costly and time consumingprocedure plus the discarded non-recyclable polymeric material isenvironmentally unfriendly.

Thus, it would be desirable to provide a low-friction surface on a hitchbearing plate of a fifth wheel, such that the low-friction surface notonly provides low friction but is also mechanically durable.

SUMMARY

Certain embodiments of the invention provides a metal matrix compositearticle. The metal matrix composite article can be any article desiringincreased lubricity at a first surface while coupled with mechanicaldurability at a second surface. Thus, the metal matrix composite articlecan be any article having a first surface and a second surface. In somecases, the first surface and the second surface are opposite surfaces.In certain cases, the metal matrix composite article is an article thatextends in a substantially horizontal plane, such as a plate or sheet.In other cases, the metal matrix composite article has athree-dimensional shape. Exemplary three-dimensional composite articlesinclude cylinder liners, bearing journals, linear bearing guides,equipment ways and ball bearing guides.

The metal matrix composite article comprises, consists essentially of,or consists of a metal component, a ceramic component and a lubriciouscomponent. As used herein, the term “metal component” refers to anymetal. In some cases, the metal component can include a metal selectedfrom aluminum, magnesium, titanium, steel and alloys thereof. As usedherein, the term “ceramic component” refers to any inorganic non-metal.In some cases, the ceramic component can include a component selectedfrom silicon carbide, alumina, silica, zirconia and mixtures thereof. Asused herein, the term “lubricious component” refers to any componentthat increases lubricity of the metal matrix composite article. In somecases, the lubricious component can include a component selected fromgraphite, tungsten disulfide, molybdenum disulfide or mixtures thereof.

The metal matrix composite article has a first surface and a secondsurface. The metal component, the ceramic component and the lubriciouscomponent each have a total volume fraction gradient extending in adirection from the first surface to the second surface. The total volumefraction gradient can range from steep gradients to shallow gradients.Also, each the lubricious component and the ceramic component have adecreasing total volume fraction gradient moving in a direction from thefirst surface to the second surface. The metal component has anincreasing total volume fraction gradient moving in a direction from thefirst surface to the second surface. In some cases, the total volumefraction gradient extends along only a portion of the article movingfrom the first surface to the second surface. In other cases, the totalvolume fraction gradient extends entirely from the first surface to thesecond surface. While in still other cases, the total volume fractiongradient can be uniquely tailored to apply specific attributes intargeted areas. Finally, total volume fraction gradient can be acontinuous gradient, a step gradient or a combination gradient thereof.

The lubricious component in the composite article has a total volumefraction gradient such that the first surface has a total volumefraction and the second surface has a total volume fraction, wherein thefirst surface total volume fraction is higher than the second surfacetotal volume fraction. In some cases, the lubricious component can havea total volume fraction of between about 1% and about 20% at the firstsurface. Also, in certain cases, the lubricious component can have asecond surface total volume fraction that is between about 0.1% andabout 100% lower than at the first surface total volume fraction. Thetotal volume fraction refers to the total volume fraction in comparisonto the entire composite article volume (or entire wear plate volume incases where the composite article is a wear plate). In some cases, thetotal volume fraction is measured using a standard SEM analyses.

Also, the ceramic component has a total volume fraction gradient suchthat the first surface has a total volume fraction and the secondsurface has a total volume fraction, wherein the first surface totalvolume fraction is higher than the second surface total volume fraction.In some cases, the ceramic component can have a total volume fraction ofbetween about 20% and about 50% at the first surface. Also, in certaincases, the ceramic component can have a second surface total volumefraction that is between about 0.1% and about 100% lower than at thefirst surface total volume fraction. Further, in some cases, thelubricious component and the ceramic component can have the same totalvolume fraction gradient.

Finally, the metal component has a total volume fraction gradient suchthat the first surface has a total volume fraction and the secondsurface has a total volume fraction, wherein the second surface totalvolume fraction is higher than the first surface total volume fraction.The metal component can also have a total volume fraction of betweenabout 80% and about 100% at the second surface. Also, in certain cases,the metal component can have a second surface total volume fraction thatis between about 0.1% and about 60% greater than at the first surfacetotal volume fraction.

In certain cases, the metal matrix composite article composite articleis a wear plate for a fifth wheel hitch. Thus, certain embodiments ofthe invention provide a fifth wheel hitch including a wear plate. Thefifth wheel hitch can be positioned in a load bed of a truck-tractor orother towing vehicle. The wear plate is positioned on an upper surfaceof a hitch bearing plate so that it directly contacts a semi-trailerbearing plate. The wear plate has an exposed first surface and a secondsurface that faces the hitch bearing plate. The first surface and thesecond surface are opposite surfaces. The exposed first surface hasincreased lubricity and the second surface has increased mechanicaldurability. Thus, the wear plate provides lubricious properties whilealso remaining mechanically durable for an extended period of time.

The wear plate can have any desired size, shape or configuration.Generally, the wear plate extends in a substantially horizontal plane.In some cases, the wear plate is a single component whereas in othercases, the wear plate includes two or more components. In certain cases,the wear plate is a single component that has a general horseshoe shape.In other cases, the wear plate includes two components, with eachcomponent having a substantially semi-circular shape or a substantiallycrescent shape. In still other cases, the wear plate is shaped toaccommodate a shape of a corresponding bearing plate.

The wear plate can secure to the hitch bearing plate by any appropriatemeans. In some embodiments, the wear plate is first formed separatelyfrom the hitch bearing plate. The wear plate is then mechanicallysecured to the hitch bearing plate using any mechanical securingmechanism known in the art. In some cases, the wear plate is secured tothe hitch bearing plate using one or more bolts. In other cases, thewear plate is welded to the hitch bearing plate using any weldingmechanism known in the art. In other embodiments, the wear plate isformed integrally to the hitch bearing plate. In these cases, the wearplate can be an integral part of the hitch bearing plate.

The wear plate comprises, consists essentially of or consists of a metalcomponent, a ceramic component and a lubricious component and has totalvolume fraction gradients as described above with reference to the metalmatrix composite article. In some embodiments, the wear plate has afirst region and a second region. The first region contains thelubricious component, the ceramic component and the metal component,wherein each component has a specified total volume fraction gradient.The second region contains only the metal component and thus does nothave a total volume fraction gradient. Also, the first region includesthe first surface that is exposed and the second region contains thesecond surface that faces the hitch bearing plate. In this embodiment,the second region serves as a monolithic backing to the first region.The monolithic backing can have a generally smooth interface with thefirst region or a textured interface with the first region. Such amonolithic backing provides additional mechanical durability to the wearplate. Also, such a textured interface can help promote adhesion betweenthe first region and the second region.

Other embodiments of the invention provide a wear plate preform having aceramic component and a lubricious component in specified densitygradients. The wear plate preform can have a ceramic component and alubricious component, wherein the wear plate preform has a first surfaceand a second surface, wherein the lubricious component has a densitythat is highest at the first surface and is lowest at the secondsurface, and wherein the ceramic component has a density that is highestat the first surface and is lowest at the second surface. The lubriciouscomponent can have a density of between about 5% and about 20% at thefirst surface. In other cases, the lubricious component has a density atthe second surface that is between about 0.1% and about 20% lower thanat the first surface. Likewise, the ceramic component can have a densityof between about 80% and about 95% at the first surface. In other cases,the ceramic component has a density at the second surface that isbetween about 0.1% and about 20% lower than at the first surface.Further, in some cases, the lubricious component and the ceramiccomponent can have the same density gradient in the preform.

Other embodiments of the invention provide methods for making a metalmatrix composite article (e.g., a wear plate). The method includes stepsof providing a slurry including a ceramic component and a lubriciouscomponent, depositing the slurry into a first mold, forming a preform,wherein the ceramic component and the lubricious component have aspecified density gradient in a flow direction, removing the preformfrom the first mold, depositing the preform into a second mold, thesecond mold being shaped as a desired metal matrix composite article(e.g., a wear plate), depositing a metal component into the second mold,wherein the ceramic component, the lubricious component and the metalcomponent form the desired metal matrix composite article (e.g., a wearplate) and removing the desired metal matrix composite article from thesecond mold.

Further embodiments of the invention provide methods for making a fifthwheel hitch with an integral wear plate. One method includes steps ofproviding a preform, wherein the preform is shaped as a wear platehaving a first surface and a second surface, wherein the preformcomprises a ceramic component and a lubricious component, wherein thelubricious component has a density that is highest at the first surfaceand is lowest at the second surface, and wherein the ceramic componenthas a density that is highest at the first surface and is lowest at thesecond surface, depositing the preform into a fifth wheel hitch bearingplate mold and depositing a metal component into the fifth wheel hitchbearing plate mold, wherein the metal component both forms the fifthwheel hitch and infiltrates the preform to form a wear plate integral tothe fifth wheel hitch.

Another method for making a fifth wheel hitch with an integral wearplate includes steps of providing a slurry including a ceramic componentand a lubricious component, depositing the slurry into a first mold,forming a preform, wherein the ceramic component and the lubriciouscomponent have a specified density gradient in a flow direction,removing the preform from the first mold, depositing the preform into asecond mold, the second mold being shaped as a wear plate, depositing ametal component into the second mold, wherein the ceramic component, thelubricious component and the metal component form the wear plate,removing the wear plate from the second mold, inserting the wear plateinto a fifth wheel hitch bearing plate mold and depositing a fifth wheelhitch forming material into the fifth wheel hitch bearing plate moldsuch that the fifth wheel hitch forming material surrounds the wearplate.

These and various other features and advantages will be apparent from areading of the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings illustrate some particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not to scale (unless so stated) and are intended foruse in conjunction with the explanations in the following detaileddescription. Some embodiments will hereinafter be described inconjunction with the appended drawings, wherein like numerals denotelike elements.

FIG. 1 is a perspective view of a fifth wheel hitch having two wearplate components that are mechanically secured to a hitch bearing plate.

FIG. 2 is a side cross-sectional view of a fifth wheel hitch of FIG. 1.

FIG. 3 is a perspective exploded view of a wear plate component of FIG.1.

FIG. 4 is a perspective view of the fifth wheel hitch of FIG. 1, whereinportions of the wear plate components are exposed to show the underlyingmonolithic backings.

FIG. 5 is a side cross-sectional view of a wear plate componentaccording to one embodiment.

FIG. 6 is a side cross-sectional view of a wear plate componentaccording to another embodiment, the wear plate component having amonolithic backing.

FIG. 7 is a side cross-sectional view of a wear plate componentaccording to another embodiment, the wear plate component having aplurality of bumps extending into the monolithic backing.

FIG. 8 is a process chart showing steps in a method of providing a wearplate on a fifth wheel hitch plate according to one embodiment.

FIG. 9 is a process chart showing steps in a method of forming a wearplate according to one embodiment.

FIG. 10 is a side cross-sectional view of a wear plate preformpositioned inside of a wear plate mold cavity according to oneembodiment, the wear plate preform being positioned directly on top of awear plate mold cavity surface.

FIG. 11 is a side cross-sectional view of a wear plate preformpositioned inside of a wear plate mold cavity according to anotherembodiment, wherein a sacrificial preform separates the wear platepreform from a wear plate mold cavity surface.

FIG. 12 is a side cross-sectional view of a wear plate preformpositioned inside of a wear plate mold cavity according to anotherembodiment, the wear plate preform having a plurality of bumpsseparating the wear plate preform from a wear plate mold cavity surface.

FIG. 13 is a process chart showing steps in a method of forming a wearplate that is integral to a fifth wheel hitch plate according to oneembodiment.

FIG. 14 is a process chart showing steps in a method of forming a wearplate that is integral to a fifth wheel hitch plate according to anotherembodiment.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description provides somepractical illustrations for implementing some embodiments of the presentinvention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements, and allother elements employ that which is known to those of ordinary skill inthe field of the invention. Those skilled in the art will recognize thatmany of the noted examples have a variety of suitable alternatives.

FIGS. 1-4 illustrate a fifth wheel hitch 100 according to one embodimentof the invention. The fifth wheel hitch 100 includes a hitch bearingplate 10 having an upper surface 12. The hitch bearing plate 10 has agenerally centrally located kingpin hole 14. The hitch bearing plateupper surface 12 includes two low-friction and mechanically durable wearplate components 16 a, 16 b. Skilled artisans will understand that whilethe embodiment if FIGS. 1-4 show two wear plate components 16 a, 16 b, asingle wear plate component or more than two wear plate components canbe used instead.

Each wear plate component 16 a, 16 b has a substantially crescent shape.Each wear plate component 16 a, 16 b also has an inner side edge 18 a,18 b that faces the direction of the kingpin hole 14. Each inner sideedge 18 a, 18 b also forms the inner or concave edge of the crescentshape. Skilled artisans will also understand that while the embodimentof FIGS. 1-4 show wear plate components 16 a, 16 b having asubstantially crescent shape, other shapes and configurations can beused instead.

Each wear plate component 16 a, 16 b can secure to the hitch bearingplate upper surface 12 by any appropriate means. In FIGS. 1-4, however,the wear plate components 16 a, 16 b are first formed separately fromthe hitch bearing plate 10 and then are mechanically secured to theupper surface with a plurality of bolts 20. The wear plate components 16a, 16 b have a first surface 22 and a second surface 24. Generally, thewear plate components 16 a, 16 b are mechanically secured to the uppersurface 12 such that the first surface 22 forms an exposed surface andthe second surface faces the hitch bearing plate 10.

FIGS. 5-7 each illustrate a different embodiment of a wear platecomponent 16 a, 16 b. In each embodiment, the wear plate component 16 a,16 b includes a first surface 22 and a second surface 24. The firstsurface 22 forms the exposed surface when the wear plate component 16 a,16 b is secured to the hitch bearing plate 10. The second surface 24faces the hitch bearing plate 10.

In FIG. 5, the entire wear plate component 16 a, 16 b, extending fromthe first surface 22 to the second surface 24, comprises, consistsessentially of, or consists of a metal component, a ceramic componentand a lubricious component. In this embodiment, the entire wear platecomponent 16 a, 16 b forms a single region. Each the metal component,the ceramic component and the lubricious component have a total fractionvolume gradient in the flow direction “x”. In other words, the totalfraction volume gradient extends entirely from the first surface 22 tothe second surface 24. The lubricious component has a total fractionvolume gradient such that the first surface total fraction volume ishigher than the second surface total fraction volume. Also, the ceramiccomponent has a total fraction volume gradient such that the firstsurface total fraction volume is higher than the second surface totalfraction volume. Finally, the metal component has a total fractionvolume gradient such that the second surface total fraction volume ishigher than the first surface total fraction volume. In FIG. 5, thelubricious component and the ceramic component have the highest totalfraction volume at the first surface 22 and the metal component has thehighest total fraction volume at the second surface 24. In each case,the total fraction volume gradients can be a continuous gradient, a stepgradient or a combination gradient thereof.

In FIG. 6, the wear plate component 16 a, 16 b includes a first region26 and a second region 28. The first region 26 includes comprises,consists essentially of, or consists of a metal component, a ceramiccomponent and a lubricious component having the total fraction volumegradients in the direction “x” as described in the embodiment of FIG. 5above. The second region 28 comprises, consists essentially of, orconsists of the metal component but not the ceramic component or thelubricious component. In other words, the total fraction volume gradientonly extends along a portion of the wear plate, i.e. only along thefirst region 26. The second region 28 does not have a total fractionvolume gradient. In this embodiment, the second region 28 serves as amonolithic backing 30 to the first region 26. Such a monolithic backing30 provides additional mechanical durability to the wear plate component16 a, 16 b. In FIG. 6, the lubricious component and the ceramiccomponent have the highest total fraction volume at the first surface 22and the metal component has the highest total fraction volume throughoutthe monolithic backing 30. Additionally, within the first region 26, themetal component has a first surface total fraction volume that is lowerthan the total fraction volume at on interface 32 between the firstregion 26 and the second region 28.

The embodiment of FIG. 7 is similar to the embodiment of FIG. 6 exceptthat the first region 26 and the second region 28 have a texturedinterface 32. In FIG. 6, the interface 32 is generally smooth and voidof any texture. However, in FIG. 7, the interface 32 includes a texturesuch as surface bumps 34. In certain cases, the monolithic backing 30 ofthe second region 28 includes a plurality of bumps 34 at the interface32. Of course, skilled artisans will understand that the first region 26can instead have the plurality of bumps at the interface 32. Thistextured interface 32 helps to promote adhesion between the first region26 and the second region 28. In FIG. 7, the lubricious component and theceramic component have the highest total fraction volume at the firstsurface 22 and the metal component has the highest total fraction volumethroughout the monolithic backing 30. Also, the metal component has afirst surface total fraction volume that is lower than the totalfraction volume at the interface.

In FIGS. 1-4, the wear plate components 16 a, 16 b each have theembodiment of FIG. 7, although this is not required. Perhaps best shownin FIG. 3 and FIG. 4, the wear plate component 16 b has a first region26 and a second region 28. The first region 26 includes the metalcomponents, lubricious component and ceramic component in a specifiedtotal fraction volume gradient. However, the second region 28 includesthe metal component but not the lubricious component or the ceramiccomponent and does not have a total fraction volume gradient. Rather,the second region 28 forms a monolithic backing 30. Also, as shown, thefirst region 26 and the second region 28 include a textured interface32. Further, the monolithic backing 30 includes a plurality of bumps 34at the interface 32.

The fifth wheel hitch 100 (including the hitch bearing plate 10)comprises, consists essentially of or consists of a fifth wheel hitchmaterial. In some cases, the fifth wheel hitch material is a metal. Incertain cases, the fifth wheel hitch material is the same as the metalcomponent. In the embodiment of FIGS. 1-4, the wear plate components 16a, 16 b include a monolithic backing 30. As such, the fifth wheel hitchmaterial can also be the same as the monolithic backing material.

In each of the wear plate component embodiments described above, themetal component can include a metal selected from aluminum, magnesium,titanium, steel and alloys thereof. The ceramic component can includecomponent selected from silicon carbide, alumina, zirconia, silica ormixtures thereof. The lubricious component can include a componentselected from graphite, tungsten disulfide, molybdenum disulfide ormixtures thereof.

In one particular embodiment, the wear plate has a ceramic componentcomprising, consisting essentially of or consisting of silicon carbide,alumina and silica, a lubricious component comprising, consistingessentially of or consisting of tungsten disulfide and graphite and ametal component comprising, consisting essentially of or consisting ofaluminum. In another embodiment, the wear plate has a ceramic componentcomprising, consisting essentially of or consisting of alumina andsilica, a lubricious component comprising, consisting essentially of orconsisting of tungsten disulfide and graphite and a metal componentcomprising, consisting essentially of or consisting of aluminum.

In another embodiment, the wear plate has a ceramic componentcomprising, consisting essentially of or consisting of silicon carbide,alumina, zirconia and silica, a lubricious component comprising,consisting essentially of or consisting of tungsten disulfide andgraphite and a metal component comprising, consisting essentially of orconsisting of aluminum. Finally, in another embodiment, the wear platehas a ceramic component comprising, consisting essentially of orconsisting of alumina, zirconia and silica, a lubricious componentcomprising, consisting essentially of or consisting of tungstendisulfide and graphite and a metal component comprising, consistingessentially of or consisting of aluminum.

Referring back to FIGS. 5-7, in certain cases, the lubricious componenthas a first surface total fraction volume in the range of about 1% toabout 20% or perhaps in the range of about 5% to about 20%. In somecases, the second surface total fraction volume is between about 0.1% toabout 100% less than the first surface total fraction volume. Also, incertain cases, the ceramic component has a first surface total fractionvolume in the range of about 20% to about 50% or perhaps in the range ofabout 15% to about 35%. In some cases, the second surface total fractionvolume is between about 0.1% to about 100% less than the first surfacetotal fraction volume. Further, in certain cases, the metal componenthas a second surface total fraction volume in the range of about 80% and100%. In some cases, the second surface total fraction volume is betweenabout 0.1% to about 60% higher than the first surface total fractionvolume.

In some cases, the lubricious component and ceramic component togethercan have a total fraction volume of between about 20% and about 40% atthe first surface and the metal component can have a total fractionvolume of between about 60% to about 80% at the first surface. Also, thelubricious component and ceramic component can together have a totalfraction volume of between about 0% and about 40% at the second surfaceand the metal component can have a total fraction volume of betweenabout 60% to about 100% at the second surface.

The wear plate total fraction volume grading feature allows for the wearplate components 16 a, 16 b to have a first surface 22 that hasincreased lubricity and a second surface 24 that has increasedmechanical durability. Thus, the wear plate components 16 a, 16 b haveboth low-friction properties and a mechanical durability that is higherthan polymeric articles or articles made from uniformly mixed compositearticles. For example, in some cases, the wear plate components 16 a, 16b may last as long as the fifth wheel hitch itself, such as up to 5years. This is much improved over a life span of a polymeric article,which typically has a life span of about 2 years.

In some embodiments, the wear plate components 16 a, 16 b have certainlocations with a thickness and/or composition that is different from theremainder of the wear plate. Such a different thickness or compositioncan provide added functionality, such as additional reinforcement andenhanced lubricious qualities. Referring back to FIG. 1, in some cases,a location of reinforcement is provided along the inner edge 18 a, 18 bof each wear plate component 16 a, 16 b. For example, in certainembodiments, the reinforcement location extends along each inner edge 18a, 18 b and extends inwardly at a predetermined distance. Each inneredge 18 a, 18 b faces the king pin hole and thus is an area where thekingpin is more likely to crash into one of the wear plate components 16a, 16 b during semi-tractor to semi-trailer connecting. In certainembodiments a reinforcement location may also or instead be located neara front edge 19 a, 19 b, of each wear plate component 16 a, 16 b nearthe tongue of the fifth wheel hitch. The reinforcement location mayextend back away from the front edge at a predetermined distance,providing reinforcement at that part of the wear plate components 16 a,16 b first likely to be hit by a misaligned kingpin.

In certain embodiments, areas within the reinforcement locations have athickness that is greater than the thickness of wear plate componentareas that are not within the location of reinforcement. In some cases,areas within the reinforcement locations have a thickness that isbetween about 0.1 inches to about 0.25 inches greater than areas outsidethe location of reinforcement. In other cases, areas outside thereinforcement locations can have a thickness of about 0.3 inches and theareas within the reinforcement locations can have a thickness that isgreater. In other embodiments, areas within the reinforcement locationshave a composition that is different than the composition areas outsidethe reinforcement locations.

Other embodiments of the invention provide a wear plate preform having aceramic component and a lubricious component in specified densitygradients. The ceramic component and lubricious component can includeany of the components already described above for the wear plate. Thelubricious component has a density gradient such that the first surfacedensity is higher than the second surface density. Also, the ceramiccomponent has a density gradient such that the first surface density ishigher than the second surface density. In some cases, the lubriciouscomponent and the ceramic component have the highest density at thefirst surface and the metal component has the highest density at thesecond surface. In each case, the density gradients can be a continuousgradient, a step gradient or a combination gradient thereof. Further, insome cases, the lubricious component and the ceramic component can havethe same density gradient in the preform.

In certain embodiments, the lubricious component in the preform has adensity of between about 5% and about 20% at the first surface. In othercases, the lubricious component has a density at the second surface thatis between about 0.1% and about 20% lower than at the first surface.Likewise, the ceramic component can have a density of between about 80%and about 95% at the first surface. In other cases, the ceramiccomponent has a density at the second surface that is between about 0.1%and about 100% lower than at the first surface.

In other embodiments, the lubricious component in the preform has atotal fraction volume in the range of about 1% to about 20% or perhapsin the range of about 5% to about 20% at the first surface. Likewise,the ceramic component can have a total fraction volume in the range ofabout 20% to about 50% or perhaps in the range of about 15% to about 35%at the second surface.

The invention also provides methods of making a fifth wheel hitch with awear plate. FIG. 8 is a process chart showing steps in a method 200 ofproviding a wear plate on a fifth wheel hitch plate according to oneembodiment. The method 200 includes separately forming a wear plate atstep 202, separately forming a fifth wheel hitch plate at step 204 andmechanically securing the wear plate to an upper surface of the fifthwheel hitch plate at step 206.

FIG. 9 is a process chart showing steps in a method 202 of forming awear plate (or components for a wear plate) according to one embodiment.While this method describes forming a wear plate, skilled artisans willunderstand that the method can be used to prepare any other desiredmetal matrix composite article. The method 200 includes providing aslurry including both a ceramic component and a lubricious component atstep 210. As used herein, the term “slurry” includes a fluid mixturesuch as a solution, colloidal mixture or colloidal suspension comprisingat least the ceramic component and the lubricious component. The slurrycan also include a binder component and a liquid component. In oneembodiment, the slurry includes the ceramic component in a weightpercent of between 2% and 20% and the lubricious component in a weightpercent of between 0.5% and 10% with the remaining weight percent beingfor the binder component and the liquid component.

In one particular embodiment, the slurry has a ceramic componentcomprising, consisting essentially of or consisting of silicon carbide,alumina and silica and a lubricious component comprising, consistingessentially of or consisting of tungsten disulfide and graphite. Inanother embodiment, the slurry has a ceramic component comprising,consisting essentially of or consisting of alumina and silica and alubricious component comprising, consisting essentially of or consistingof tungsten disulfide and graphite. In another embodiment, the slurryhas a ceramic component comprising, consisting essentially of orconsisting of silicon carbide, alumina, zirconia and silica and alubricious component comprising, consisting essentially of or consistingof tungsten disulfide and graphite. Finally, in another embodiment, theslurry has a ceramic component comprising, consisting essentially of orconsisting of alumina, zirconia and silica and a lubricious componentcomprising, consisting essentially of or consisting of tungstendisulfide and graphite.

The method 202 further includes depositing the slurry into a first moldat step 212 and forming a preform at step 214. The slurry is depositedunder pressure to form a preform that has a density that changes in aparticular flow direction. As such, the ceramic component and thelubricious component have a specified density gradient in a flowdirection. As used in connection with a preform, the term “density”refers to porosity such that a higher density indicates a lower porosityand a lower density indicates a higher porosity.

The method 202 also includes drying and firing the preform and removingthe preform from the first mold at step 216. Methods of preparing apreform having a density gradient are described in U.S. Pat. No.8,075,827, the entire contents of which are incorporated herein byreference. Any of the methods described in U.S. Pat. No. 8,075,827 canbe used to prepare the preform so that it has the specified densitygradient.

The method 202 further includes an optional step 218 of depositing athermal insulator into a second mold. Thermal insulators and methods ofdepositing thermal insulators into a mold are described in U.S. patentapplication Ser. No. 13/840,423 and U.S. patent application Ser. No.13/836,001, the entire contents of which are incorporated herein byreference. Any of the methods described in U.S. patent application Ser.No. 13/840,423 or U.S. patent application Ser. No. 13/836,001 can beused to deposit the thermal insulator into the second mold.

The method 202 also includes preheating the preform at step 220 anddepositing the preform into the second mold at step 222. The second moldis sized and shaped to form a wear plate or wear plate component. Thepreform can be preheated before being deposited into the second mold sothat the preform substantially fills the entire second mold. The method202 next includes depositing a metal component into the second mold atstep 224 and then forming a wear plate at step 226. In certain cases,step 226 of forming the wear plate can include pressurizing the secondmold so that the metal component flows through the pores in the preform.Finally, once the wear plate is formed, it can be removed from thesecond mold at step 228.

FIGS. 10-12 illustrate different preforms and portions of a second mold300 that can be used to perform the method 202 of FIG. 9. In FIG. 10, apreform 302 is deposited into the second mold 300 such that the entirepreform 302 substantially fills the mold cavity. Once the preform isdeposited into the second mold 300, a metal component 304 deposited. Themetal component flows through the pores in the preform 302. The preformand second mold of FIG. 10 produces a wear plate having an embodimentshown in FIG. 5.

In FIG. 11, a sacrificial preform 306 is first deposited into the secondmold 300 and then the preform 302 is deposited over the sacrificialpreform 306. A metal component 304 is deposited and both replaces thearea occupied by the sacrificial preform 306 and flows through the poresin the preform 302. In FIG. 11, the area occupied by the preform 302forms a first region and the area occupied by the sacrificial perform306 forms a second region of the resulting wear plate. The metalcomponent 304 thus forms a monolithic backing in the second region area.The preform and second mold of FIG. 11 produces a wear plate having anembodiment shown in FIG. 6.

In FIG. 12, the preform 302 has a textured surface 308. The texturedsurface 308 can be in the form of bumps and hollows or any other desiredtexture. The preform 302 is deposited into the second mold 300 such thata space is created between the textured surface 308 and the mold cavity.A metal component 304 is deposited and both fills in the space betweenthe textured surface 308 and mold cavity and flows through the pores inthe preform 302. In FIG. 12, the area occupied by the preform 302 formsa first region and the space between the textured surface 308 and moldcavity forms a second region of the resulting wear plate. The metalcomponent 304 thus forms a monolithic backing in the second region area.The first region and the second region also have a textured interface308. The preform and second mold of FIG. 12 produces a wear plate havingan embodiment shown in FIG. 7.

FIG. 13 is a process chart showing steps in a method 400 of forming awear plate that is integral to a fifth wheel hitch plate according toone embodiment. The method 400 includes performing steps 210 through 216of FIG. 9 at step 402. Next, the method 400 includes preheating thepreform at step 404 and depositing the preform into a fifth wheel hitchbearing plate mold at step 406. Skilled artisans will understand thatthe fifth wheel hitch bearing plate mold can be either a mold for theentire fifth wheel or a mold for the hitch bearing plate. In some cases,at step 406, the preform is deposited into a fifth wheel hitch bearingplate mold so that the first surface 22 faces the mold cavity. At step408, the method 400 includes depositing a metal component into the fifthwheel hitch bearing plate mold. In other cases, step 408 is performedbefore step 406. Here, at step 408, the metal component is firstdeposited into the fifth wheel hitch bearing plate mold. At step 406,the preform is then deposited on top of the metal component such thatthe first surface 22 faces upward and it floats or suspends in the metalcomponent. Next, additional metal component is deposited to infiltratethe preform. Finally, in some cases, the fifth wheel hitch material andthe metal component are the same and this ensures integration of thewear plate within the fifth wheel hitch bearing plate.

FIG. 14 is a process chart showing steps in a method 500 of forming awear plate that is integral to a fifth wheel hitch plate according toanother embodiment. The method 500 includes performing steps 210 through228 of FIG. 9 at step 502. Next, the method 500 includes inserting thewear plate into a fifth wheel hitch bearing plate mold at step 504. Thewear plate in this method 500 serves as an insert. In some cases, atstep 504, the wear plate is deposited so that the first surface 22 facesthe mold cavity. At step 506, the method 500 includes depositing a fifthwheel hitch material into the fifth wheel hitch bearing plate mold. Inother cases, step 506 is performed before step 504. Here, at step 506,the metal component is first deposited into the fifth wheel hitchbearing plate mold. At step 504, the wear plate is then deposited on topof the metal component such that the first surface 22 faces upward andthe wear plate floats or suspends in the metal component. The fifthwheel hitch material can be the same as the metal component or it can bedifferent. Finally, at step 508, the method includes forming a fifthwheel hitch bearing plate that includes an integral wear plate.

Thus, embodiments of the invention are disclosed. Although the presentinvention has been described in considerable detail with reference tocertain disclosed embodiments, the disclosed embodiments are presentedfor purposes of illustration and not limitation and other embodiments ofthe invention are possible. One skilled in the art will appreciate thatvarious changes, adaptations, and modifications may be made withoutdeparting from the spirit of the invention and the scope of the appendedclaims.

What is claimed is:
 1. A fifth wheel hitch, comprising: a hitch bearingplate having an upper surface; and a wear plate secured to the uppersurface of the hitch bearing plate; wherein the wear plate consistsessentially of a metal matrix composite that comprises a metalcomponent, a ceramic component and a lubricious component, wherein thewear plate has a first surface and a second surface, wherein the firstsurface is an exposed surface and the second surface faces the uppersurface of the hitch bearing plate, wherein the lubricious component hasa total volume fraction that is highest at the first surface and islowest at the second surface, wherein the ceramic component has a totalvolume fraction that is highest at the first surface and is lowest atthe second surface, and wherein the metal component has a total volumefraction that is highest at the second surface and is lowest at thefirst surface.
 2. The fifth wheel hitch of claim 1, wherein thelubricious component in the wear plate has a total volume fraction thatis from 1% to 20% at the first surface.
 3. The fifth wheel hitch ofclaim 1, wherein the wear plate includes the lubricious component at thesecond surface at a total volume fraction that is from 0.1% to 100%lower than at the first surface.
 4. The fifth wheel hitch of claim 1,wherein the ceramic component in the wear plate has a total volumefraction that is from 20% to 50% at the first surface.
 5. The fifthwheel hitch of claim 1, wherein the wear plate includes the ceramiccomponent at the second surface at a total volume fraction that is from0.1% to 100% lower than at the first surface.
 6. The fifth wheel hitchof claim 1, wherein the metal component in the wear plate has a totalvolume fraction that is from 80% to 100% at the second surface.
 7. Thefifth wheel hitch of claim 1, wherein the wear plate includes the metalcomponent at the second surface at a total volume fraction that is from0.1% to 60% greater than at the first surface.
 8. The fifth wheel hitchof claim 1, wherein the metal component of the wear plate comprises ametal selected from the group consisting of aluminum, magnesium,titanium, steel and alloys thereof.
 9. The fifth wheel hitch of claim 1,wherein the ceramic component of the wear plate comprises a componentselected from the group consisting of silicon carbide, alumina, silica,zirconia and mixtures thereof.
 10. The fifth wheel hitch of claim 1,wherein the lubricious component of the wear plate comprises a componentselected from the group consisting of graphite, tungsten disulfide,molybdenum disulfide and mixtures thereof.
 11. The fifth wheel hitch ofclaim 1, wherein the wear plate is mechanically secured to the uppersurface of the hitch bearing plate.
 12. The fifth wheel hitch of claim 1wherein the wear plate is integral to the upper surface of the hitchbearing plate.
 13. The fifth wheel hitch of claim 1, wherein at leastone of the ceramic component, the lubricious component, and the metalcomponent comprises a volume fraction gradient.
 14. The fifth wheelhitch of claim 13, wherein each of the ceramic component, the lubriciouscomponent, and the metal component comprises a volume fraction gradient.15. A fifth wheel hitch, comprising: a hitch bearing plate having anupper surface; and a wear plate secured to the upper surface; whereinthe wear plate comprises a metal component, a ceramic component and alubricious component, wherein the wear plate has a first surface and asecond surface, wherein the first surface is an exposed surface and thesecond surface faces the upper surface of the hitch bearing plate,wherein the lubricious component has a total volume fraction that ishighest at the first surface and is lowest at the second surface,wherein the ceramic component has a total volume fraction that ishighest at the first surface and is lowest at the second surface,wherein the metal component has a total volume fraction that is highestat the second surface and is lowest at the first surface, wherein thewear plate comprises a first region and a second region, wherein thefirst region comprises the metal component, the ceramic component andthe lubricious component, and wherein the second region consistsessentially of the metal component.
 16. The fifth wheel hitch of claim15, wherein the wear plate comprises a textured interface between thefirst region and the second region.
 17. A wear plate for a fifth wheelhitch, comprising: a metal component, a ceramic component and alubricious component, wherein the wear plate has a first surface and asecond surface, wherein the first surface is an exposed surface and thesecond surface is opposite the first surface, wherein the lubriciouscomponent has a total volume fraction that is highest at the firstsurface and is lowest at the second surface, wherein the ceramiccomponent has a total volume fraction that is highest at the firstsurface and is lowest at the second surface, wherein the metal componenthas a total volume fraction that is highest at the second surface and islowest at the first surface, and wherein at least one of the ceramiccomponent, the lubricious component, and the metal component comprises avolume fraction gradient extending at least partially between the firstsurface and the second surface.
 18. The wear plate of claim 17, whereinthe lubricious component in the wear plate has a total volume fractionthat is from 1% to 20% at the first surface.
 19. The wear plate of claim17, wherein the wear plate includes the lubricious component at thesecond surface at a total volume fraction that is from 0.1% to 100%lower than at the first surface.
 20. The wear plate of claim 17, whereinthe ceramic component in the wear plate has a total volume fraction thatis from 20% to 50% at the first surface.
 21. The wear plate of claim 17,wherein the wear plate includes the ceramic component at the secondsurface at a total volume fraction that is from 0.1% to 100% lower thanat the first surface.
 22. The wear plate of claim 17 wherein the metalcomponent in the wear plate has a total volume fraction that is from 80%to 100% at the second surface.
 23. The wear plate of claim 17, whereinthe wear plate includes the metal component at the second surface at atotal volume fraction that is from 0.1% to 60% greater than at the firstsurface.
 24. The wear plate of claim 17, wherein the metal component ofthe wear plate comprises a metal selected from the group consisting ofaluminum, magnesium, titanium, steel and alloys thereof.
 25. The wearplate of claim 17, wherein the ceramic component of the wear platecomprises a component selected from the group consisting of siliconcarbide, alumina, silica, zirconia and mixtures thereof.
 26. The wearplate of claim 17, wherein the lubricious component of the wear platecomprises a component selected from the group consisting of graphite,tungsten disulfide, molybdenum disulfide and mixtures thereof.
 27. Awear plate for a fifth wheel hitch, comprising: a metal component, aceramic component and a lubricious component, wherein the wear plate hasa first surface and a second surface, wherein the first surface is anexposed surface and the second surface is opposite the first surface,wherein the lubricious component has a total volume fraction that ishighest at the first surface and is lowest at the second surface,wherein the ceramic component has a total volume fraction that ishighest at the first surface and is lowest at the second surface, andwherein the metal component has a total volume fraction that is highestat the second surface and is lowest at the first surface, wherein thewear plate comprises a first region and a second region, wherein thefirst region comprises the metal component, the ceramic component andthe lubricious component, and wherein the second region consistsessentially of the metal component.
 28. The wear plate of claim 27,wherein the wear plate comprises a textured interface between the firstregion and the second region.